About e1RM

e1RM is an indie strength training calculator built by a lifter who got tired of single-formula apps. The "1RM" you see in most online calculators is technically an e1RM — an estimated one rep max derived from a submaximal set. We named the site after the thing we're actually calculating.

What makes e1RM different

• Six formulas, side by side. Epley, Brzycki, Lombardi, O'Conner, Mayhew, and Wathan. The spread between them tells you how much uncertainty to expect from your input set.
• Cite-able sources. Every formula links to its original publication year and paper. Every strength standard explains how it was calculated. No magic numbers.
• No signup, no ads, no email gate. Calculators stay free and stay open.

Who builds this

e1RM is built by an indie developer who lifts. The math behind every calculator is double-checked against the original source papers (Epley 1985, Brzycki 1993, Lombardi 1989, Mayhew 1992, Wathan 1994). Training percentages and intensity recommendations are pulled from standard intermediate barbell programs (5/3/1, nSuns, Texas Method, GZCL) rather than invented.

Contact

Have a correction, a feature request, or a paper we should reference? Email feedback@e1rm.com.

Roadmap

Currently building out per-lift content, formula-specific deep dives, and a Chinese-language version. Subscribe to the newsletter at the bottom of any page for monthly updates on what's new.